The present invention relates generally to storage units, and more particularly to units configured for high density storage, such as those configured for storage of large volumes of files and the like.
Traditionally, four-drawer filing cabinets, such as that disclosed in U.S. Pat. No. 5,251,974, have been used for storing file folders. Filing cabinets are still a popular method of storage; however, the increase in the use of computers in business has resulted in a substantial increase in the amount of paperwork generated on a daily basis. Storage of the additional paperwork has become a problem due to the additional space required for filing cabinets, storage boxes and the like. Increased storage requirements, coupled with the corresponding space requirements for storage and access, have resulted in increased costs for businesses.
Accordingly, it will be appreciated by those skilled in the art that it is desirable to have a system for storing high volumes of files, manuals, books, records and the like, that uses a minimum amount of physical space. To this end, there have been attempts to devise such devices. Open shelving, as disclosed in U.S. Pat. No. 5,127,340, was one of the first products utilized to store large amounts of materials. Unlike traditional filing cabinets, open shelving more effectively utilizes the available vertical space. However, like filing cabinets, open shelving units are stationary and, therefore, require a certain amount of access space between rows.
The power file, as disclosed in U.S. Pat. No. 3,442,564, utilizes vertical space more effectively than open shelving in that shelves are raised and lowered by a motor-driven chain and sprocket system. While these systems have gained popularity, they are extremely costly to maintain.
A rotary file, as disclosed in U.S. Pat. No. 5,312,181, has storage capacity on both the front and back sides. The back side is accessed by pivoting the shelving unit. These units have also gained popularity; however, due to the manner in which files are accessed, they require a significant amount of floor space which usually does not justify the cost.
A lateral slide storage system, as disclose in U.S. Pat. No. 5,205,627, provides high density storage through side-to-side lateral movement of the unit. The unit generally includes two rows of shelving, one in front and one in back. The back row is accessed by sliding part of the front row to the side. These units are generally more cost effective than the aforementioned systems; however, they are limited to a depth of only two rows. Moreover, aisle space in front of the unit is required to access the back row.
Most recently, mobile systems, as disclosed in U.S. Pat. No. 4,944,231, have become the most popular method of high density storage. In this system, open stationary shelves are attached to a movable carriage which rolls with wheels along a stationary track. All the rows of shelving can be rolled together in order to compact the shelving, thus allowing more rows. One drawback associated with this system is that installation of the system is extremely labor-intensive and, thus, costly. Another drawback is that an aisle space within the system must be left open at all times, consuming additional floor space.
U.S. Pat. No. 4,123,126, issued to Querengasser, is directed to a compact shelving apparatus consisting of a cluster of elongated, upstanding stacks of shelves juxtaposed side by side. The shelves are accessible by mounting each elongated stack on an elongated carriage having rear rollers guided in elongated floor tracks coextensive in length and width with the stack and hidden thereunder. Plastic tired wheels are provided under the front of the carriage so that the carriage and stack can be moved endwise on a track out of the cluster to expose the open side shelves. Front shelves may be added to increase storage capacity. A removable crank on the front end, through twist-belt power transmission, advances and retracts each stack. One drawback associated with the Querengasser apparatus is that the wheels on the front end of the carriage may damage the floor or support surface due to the weight of the shelving unit and its contents. Thus, the weight on the wheels may cause undesirable indentations or track marks in the floor due to the extension and retraction of the shelving unit from the cluster.
While the patents referenced hereinabove generally disclose systems for high density storage, each has drawbacks in terms of available storage space, floor space requirements and access requirements. What is needed, then, is a system that enables high density storage while utilizing minimal storage and access space.